Interlocking switch



Aug. 21, 1923.

L. c. WESCOAT INTERLOGKING SWITCH Filed Nov. 15, 1919 Patented Aug. 21,1923.

UNITED STATES LEWIS C. WESCOAT, OF ELMHURST, NEW YORK,

COMPANY, INCORPORATED, OF NEW YORK, N. Y.,

ASSIGNOR TO WESTERN ELECTRIC A CORPORATION OF NEW YORK.

INTERLOCKING SWITCH.

Application filed November 15, 1919. Serial No. 338,219.

To all whom it may concern:

Be it known that I, Lnwrs C. WESCOAT, a citizen of the United States,residing at Elmhurst, in the county of Que ens, State of New York, haveinvented certain new and useful Improvements in Interlocking Switches,of which the following is a full, clear, concise, and exact description.

This invention relates to electric switches and more particularly tointerlocking switches,'and has for its object the provision of meanswhereby two or are made interdependent so that each of said switches canbe operated only in a definite order with respect to the other switchesin the grou The app ication of this invention to a pair of knifeswitches for example, comprises an arm attached to one of the switchesprojecting laterally therefrom andoverlaping the other switch. The'twoswitches, of course, are mounted adjacently on a common. base member orpanel. Both switches are thus interdependent in operation; the secondswitch cannot be opened until the first switch has been opened andconversely, the first switch cannot be closed until the second switchhas been closed.

While this invention is applicable to any desired number of switches ina application to a grou comprismg more than two switchesmere y resultsin amultn plication of the parts as applied to only two switches.

In the drawing, Nos. 1, 2 and 3 aresingle blade double-throw knifeswitches of the continuous contact type, two of which are provided withprojecting arms 4 and 5, each am being arranged to overlap :the switchadjacent to that to which the arm is attached. The switch blades areV-shaped and are fulcrumed at the points 18, 19 and '20respectively.Nos. 6 to 17 inclusive are spring contacts cooperating with the blades0f the switches. These contacts are arranged in pairs, each pairconsisting of a long and a short contact, the reason for which will beclear from a description of the associated circuit hereinafter. There isshown in the drawing associated with the switches, a typical circuitillustrating an example wherein these interlocking switches areparticularly applicable. B

battery consisting of a'number of cells and will be hereinafter referredto as the main more switches oup, its

is a. storage of single cells or as the latter declines,- ne or more ofthe end cells. It is required that the addition of end cells shall beterrupting must be done without end cells.

With the three switches l, 2 and 3 closed in the lower position, mainbatte B is connected to the terminals T and T the circuit being fromterminal T, conductor 21, main battery B conductor 22 to point 23,conductor 32 to s ring contact 9, the blade of switch 1 to fu crum point18, conductor 24, spring contact 13, the blade of switch. 2 to fulcrumpoint 19, conductor 25, spring contact 17, the blade of switch 3 tofulcrum point 20, conductor 26 to terminal T Now, when the main batteryB has discharged .to such an extent that the voltage between theterminals T and T has dropped below a certain limit, one or more of theend cells must be added in series with the main battery to maintain thevoltage and this is accomplished by throwing one or more of the switchesinto the upper position. It will be seen that, on account ofinterference imposed by the projecting arms 4.- and 5, switches 2 and 3cannot be thrown into the upper position until switch 1 has been thrownswitches 2 and 3 can only be thrown into the upper position in the order2-3. To add end cell battery B in series with main battery B switch 1 isthrown from the lower to the upper position. The blade of this switchwill make contact with the spring contact 7 before breaking with s ring0on tact 9 and the end cell battery 2 will be momentarily shuntedthrough the resistances R and R. A further movement of the switch 1 intothe upper position will bring its blade into contact with the springcontact 8, but before contact is made with spring contact 8, it will bebroken with spring contact 9, when B will be shunted accomplishedWithout inshort-circuiting the are auxiliary storthe circuit and this,of course,

into that position and likewise throu h R only, otherwise the end cellbattery 2 would be short-circuited. The resistances R to to limit thedischarge of the end cells to their normal discharge current during thebrief time that the end cells are shunted. through these resistanceswhen the switches are thrown from one position to the other. With theswitch 1. inthe upper position and the switches 2 and 3 in the lowerposition, the circuit between terminals T and T will be as follows:Terminal T, conductor 21, battery 3, conductor 22, conductor 27, batteryB conductor 29, conductor 28, spring contact 8, blade of switch 1 tofulcrum point 18 and from there on to terminal. T as before enumerated.\Vhen switch 2 is thrown into the upper position, end cell battery 13 isconnected in series with main battery B and end cell battery B Battery Bwill be shunted momentarily by the resistances R and R just as battery Bwas shunted by resistances R and R With switches 1 and 2 in the upperposition and switch 3 in the lower position, a circuit between theterminals T and T will be as follows: Terminal T, conductor 21, battery13, conductor22, conductor 27, battery B conductor29, battery Bconductors 30 and 31, spring contact 12, blade of switch 2 to fulcrumpoint 19 and thence to terminal T as before enumerated. The addition tothe circuit of end cell batter 3* is accomplished by throwin the switc 3into the upper position and will not require further description. Theoperation of disconnecting the end cell batteries from the circuit isaccomplished by throwing the switches into the lower positlon in theorder 3, 2, 1, that is, in the order reversed to that in which theswitches are thrown into the upper position. During the transition ofswitch 1 from the lower to the upper position, after the blade ofswitch1 has broken with spring contact 9 and ,before it has broken with springcontact 6, the circuit between tern1inals T and T is momentarilymaintained through the resistance R and the voltage between T and T isof course, momentarily reduced thereby. In order that this reduc- Rinclusive are designed 1,4,ee,sa4

tion in Volta e may not be excessive, the resistance'cf 1% must be assmall as possible consistent. with the fact that it must be large enoughto prevent excessive discharge of the end cell battery B during thebrief period in which said battery is shunted. by said resistance. Forsimilar reasons, all the other shunt resistances must be as small as therequirements will permit. Now if the arms t and 5 were not provided, itwill be seen that the switches 1, 2 and 3 would be separately operableand they could be thrown from one position to the other without regardto sequence. If, for.example, switch 3 were thrown into the upperposition while switches 1 and 2 were still in the lower position, thebatteries B B and B in series would be momentarily shunted through thesingle resistance R and as this resistance is small, being intended toshunt only one end cell, the result would be a momentary excessdischarge from the end cell batteries.

What is claimed is:

1. A switch mechanism comprising a plurality of V-shaped knife bladeswitches interlocked so that they may be thrown from one position toanother only in sequence, two sets of stationary contacts for eachblade, each set cooperating with one of the arms of the blade and eachset consisting of a long and short terminal connected together through aresistance, said long terminal situated nearer the pivotal point of theblade than the short terminal.

2. A switch mechanism comprising a bracket, a switch blade fulcrumedthereto and having arms extending on both sides of the fulcrum point,and a set of stationary contacts disposed on each side of said fulcrumpoint, each setcooperating with one of said arms and each. setconsisting of a long and short terminal connected together through aresistance, .said long terminal situated nearer the fulcrum point of theblade than the short terminal.

In witness whereof, I hereunto subscribe my name this 11th day ofNovember, A. D.

LEWIS o. WESCOAT.

